The water data fits perfectly with NASA's mission to discover whether Mars can, or has ever been able to, support life. Since water is one of the key ingredients to supporting life as we know it, scientists are heartened by the information and looking for other critical elements, such as carbon-containing chemicals that can be a source for organic life.

"This new report and others are continuing to reveal a more complex Mars than previously appreciated, with at least some areas more likely to reveal signs of ancient life than others," said Rich Zurek, a project scientist with NASA's Mars Reconnaissance Orbiter. The orbiter sent back data about the floor of what's being called the McLaughlin Crater.

The crater, which is 57 miles wide and 1.4 miles deep, has a bottom comprised of layered, flat rocks that contain carbonate and clay minerals that form in the presence of water.

NASA scientists said they believe the carbonates and clay formed in a groundwater-fed lake that could have been a habitat for life.

"Taken together, the observations in McLaughlin Crater provide the best evidence for carbonate forming within a lake environment, instead of being washed into a crater from outside," said Joseph Michalski, a research scientist with the Planetary Science Institute in Tucson, Ariz.

Equipped with 10 scientific instruments, Curiosity has the most advanced payload of scientific gear, including chemistry instruments, environmental sensors and radiation monitors, ever used on the surface of Mars. The payload is more than 10 times larger than those of earlier Mars rovers.

Last summer, the space agency also announced that it plans to explore the interior of Mars to discover why that planet developed so differently from Earth. That mission, dubbed Insight, is designed to discover whether the core of Mars is solid or liquid like Earth's, and why Mars' crust is not divided into tectonic plates that drift as they do on Earth.